1. Field of the Invention
The present invention relates to pendant controls, specifically to selectively block access to certain control buttons of an overhead crane pendant while leaving others accessible.
2. Background of the Prior Art
A pendant is a control unit comprised of control buttons that perform different tasks. The pendant is attached to equipment by a cable for controlling the equipment. Pendants are used for controlling a variety of equipment, one example being an overhead crane in a factory setting. The pendant is suspended by the crane in a position for reaching by a user. The controls on the pendant allow movement of the crane hook up and down as well as moving the entire crane in two different directions.
When a break down happens in an overhead crane, the crane may be inoperable until repaired. A repairman may not be available, or it may be necessary to order parts, thus placing the crane out of commission for some time. During this down time the crane typically shouldn't be used, depending on the type of problem. While one can cut off the power to the crane, this normally can be done only at the overhead crane itself, involving a worker climbing up to the overhead rails. It might be necessary while the crane is down to use it to some extent, perhaps just to move it out of the way of other work taking place. If the power is cut off, this requires a worker to climb up to the unit on the overhead rails, thus is time consuming. Consequently, it has been continuously observed when a repairman is not available that control buttons on pendants are wrapped with tape by field personnel not familiar with code rules, regulations or even their own company policies on lock-out/tag-out procedures if the overhead crane is partially inoperable, indicating that those particular control buttons are not to be used. Accidentally, however, an operator could press the wrong control buttons, and damage to the crane or an accident may occur. Also, the tape might be wrongly removed, allowing access to all of the buttons while the crane is still partly inoperable. Therefore, a need to more securely lock out the control buttons of the pendant is needed.